scholarly journals Position Control Study on Pump-Controlled Servomotor for Steam Control Valve

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 221
Author(s):  
Guishan Yan ◽  
Zhenlin Jin ◽  
Tiangui Zhang ◽  
Penghui Zhao
Keyword(s):  
Control Strategy ◽  
Position Control ◽  
Sliding Mode ◽  
Variable Structure Control ◽  
Control Valve ◽  
Good Control ◽  
Variable Structure ◽  
Structure Control ◽  
Sliding Mode Variable Structure ◽  
Valve Control

In steam turbine control and actuation, the steam control valve plays a key role in operability and reliability. The electrohydraulic regulating system for the steam control valve, usually called the servomotor, needs to be reliable and high performing under nonlinear excitation interference in actual conditions. Currently, electrohydraulic servo valve control technology is widely used in servomotors. Although this technology has good control performance, it still has some technical defects, such as poor antipollution ability, low energy efficiency, large volume size, and limited installation space. Aiming at the abovementioned technical shortcomings of electrohydraulic servo valve control technology, a servomotor-pump-hydraulic cylinder volume control scheme is proposed in this paper, forming a pump-controlled servomotor for the steam control valve. By analyzing the working principle of the pump-controlled servomotor position control in the steam control valve, the mathematical model of a pump-controlled servomotor for the steam control valve is established. The sliding mode variable structure control strategy is proposed, and the variable structure control law is solved by constructing a switching function. To verify the performance of the proposed control method, experimental research was conducted. The research results show that the proposed sliding mode variable structure control strategy has a good control effect, which lays the theoretical and technical foundation for the engineering application and promotion of pump-controlled servomotors for steam control valves and helps the technical upgrade and product optimization of steam turbines.

scholarly journals AUTO LOAD-LEVELLING CONTROL OF A LARGE SPRAYER CHASSIS USING THE SLIDING MODE METHOD

2021 ◽  
pp. 65-80
Author(s):  
Chen Yu ◽  
Wu Jun ◽  
Zhang Shuo ◽  
Chen Jun ◽  
Xia Hui ◽  
...  
Keyword(s):  
Working Conditions ◽  
Control Method ◽  
Sliding Mode ◽  
Variable Structure Control ◽  
Good Control ◽  
Variable Structure ◽  
Wheel Load ◽  
Structure Control ◽  
Air Suspension ◽  
Sliding Mode Variable Structure

When a sprayer travels on a ramp or a rough road, the load exerted on each wheel changes. If an unbalanced wheel load is maintained for long periods of time, the wheels may slip, the sprayer’s manoeuvrability is affected, and a rollover accident may occur. In this study, the air suspension of a self-propelled sprayer chassis was investigated, and the potential load imbalance conditions of the sprayer suspension were analysed. A mathematical model of the inflation/deflation of the suspension was established based on air nonlinear thermodynamics and vertical dynamics theory and a ¼-scale vertical dynamics model of the sprayer chassis was developed. A control strategy to balance the sprayer’s wheel load was developed. Considering the nonlinear characteristics of the air suspension, a sliding mode variable structure control method was used to balance the wheel load. Simulation experiments were conducted under different working conditions. The simulation results showed that the sliding mode variable structure control provided good control response and precision. The proposed auto load-levelling controller was tested under different working conditions, including different roll and pitch angles and navigating a rough road; the controller successfully changed the load on each spring to ensure that the sprung mass of the suspension was equal and the wheel load was balanced. The results of this study provide reference information for auto load-levelling control of large sprayers.

ABS Sliding Mode Variable Structure Control Based on Index Reaching Law

2014 ◽  
Vol 915-916 ◽  
pp. 439-443
Author(s):  
Sheng Yi Xuan ◽  
Chuan Xue Song ◽  
Guang Wei Meng
Keyword(s):  
Sliding Mode Control ◽  
Control Strategy ◽  
Sliding Mode ◽  
Variable Structure Control ◽  
Variable Structure ◽  
Active Safety ◽  
Structure Control ◽  
Reaching Law ◽  
Mode Control ◽  
Sliding Mode Variable Structure

ABS(antilock brake system) is one of the most important active safety technology for modern vehicles which could enhance vehicle active safety. In this paper, an improved sliding mode control method based on reaching law has been proposed to solve the vibration problem in traditional sliding mode control. The ABS control strategy has been designed based on the sliding mode variable structure control. On this basis, the ABS single wheel depending on control strategy has been designed to ensure the braking stability. By hardware-in-loop simulation, the results demonstrate that ABS sliding mode variable structure control could enhance braking stability performance and improve the control effect on high friction and low friction road.

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